"Your beauty has blown me away". = Your beauty has made a tremendous impression on me. to blow (someone) away is a phrasal verb which means that something has impressed someone very, very much. You could also say, "I'm blown away by your beauty." Please look here for still other meanings of the phrase: http://www.macmillandictionary.com/dictionary/american/blow-away

"To be blown away" can mean: 1. Something (good or bad) that completely shocks you and you almost don't know how to deal with it. 2. To be shot and killed (either in real life or a video game) It's based on context and no one will confuse your meaning. :-) You can say that "Your beauty blows me away" or "Your beauty has blown me away". You can also make the phrase negative by using it with something bad. "The news of his failure blew me away." But it can sound flippant so it would probably be best not to use it for really terrible news.